Ferromagnetic spin alignment in head-to-tail coupled oligo(1, 4-phenyleneethynylene)s and Oligo(1,4-phenylenevinylene)s bearing pendant p-phenylenediamine radical cations

The intramolecular and long-range ferromagnetic coupling between p-phenylenediamine radical cations in head-to-tail coupled oligo(1, 4-phenyleneethynylene)s and oligo(1,4-phenylenvinylene)s between neighbors and next-nearest neighbors is described. UV/vis/near-IR experiments show that the radical cations are localized in the pendant p-phenylenediamine units of the conjugated oligomers. The ESR spectra of these oligo(1,4-phenyleneethynylene) and oligo(1, 4-phenylenvinylene) di(radical cation)s are consistent with those of a triplet state. A linear behavior is observed for the doubly integrated ESR intensity of the DeltaM(s) = +/-1 and DeltaM(s) = +/-2 signals with the inverse temperature (I approximately 1/T), consistent with Curie's law. This behavior indicates a triplet ground-state diradical with a large triplet-singlet energy gap or possibly a degeneracy of singlet and triplet states.     

Dependence of the heats of adsorption on the chemical potentials of adsorbent and adsorbate

The heats of adsorption of gases on metals show a rather complex dependence on the chemical potentials of the solid and gas participating in the process.

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Variation of surface properties and textural features of spinel ZnAl2O4 and perovskite LaMnO3 nanoparticles prepared via CTAB-butanol-octane-nitrate salt microemulsions in the reverse and bicontinuous states

Two binary oxides, a spinel, ZnAl2O4, and a typical perovskite, LaMnO3, have been prepared via CTAB-1-butanol-n-octane-nitrate salt microemulsion in the reverse and bicontinuous states. The exact point of the reverse and bicontinuous states of the microemulsion used in the synthesis was determined by conductivity experiments. The materials obtained after heating at 800 degrees C were characterized by XRD analysis for their crystal structure, N2 porosimetry for their surface area and porosity, and SEM and TEM photography for their texture. The ZnAl2O4 spinel obtained via the reverse microemulsion appears in SEM in a more fragmented form and with a higher specific surface area (143.7 m(2)g(-1)), compared to the corresponding solid prepared via the bicontinuous microemulsion, which appears more robust with lower surface area (126.7 m(2)g(-1)). Nevertheless both materials reveal in TEM a sponge-like structure. The perovskite materials LaMnO3 prepared via the reverse microemulsion showed in SEM a peculiar doughnut-like texture, each doughnut-like secondary particle having a diameter of 2 microm. The corresponding sample developed via the bicontinuous microemulsion showed in SEM uniform secondary particles of size approximately 0.2 microm. Both perovskite samples LaMnO3 appear well crystallized with relative low surface areas, 23.7 m(2)g(-1) for the reverse sample and 10.9 m(2)g(-1) for the bicontinuous one. The TEM photographs reveal that both of them, of reversed and bicontinuous origin, are made up of primary nanoparticles in the size range 40-100 nm. In SEM those materials showed a different secondary structure.     

Supramolecular phthalocyanine dimers based on the secondary dialkylammonium cation/dibenzo-24-crown-8 recognition motif

[formula: see text] New unsymmetrically substituted DB24C8-phthalocyanines, which are able to form complexes with suitable dialkylammonium cations, have been prepared. These complexes most probably have a pseudorotaxane geometry.